XML 61 R49.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Fair Value Measurements Long-term Debt (Details) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2018 | Mar. 31, 2017 | Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Impairment of Proved Oil and Gas Properties | $ 0 | $ 0 |
6.50% Senior Notes Due 2021 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 6.50% |  |
Senior Notes, face amount |  |  | $ 344,611
6.125% Senior Notes Due 2022 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 6.125% |  |
Senior Notes, face amount |  |  | 561,796
6.50% Senior Notes Due 2023 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 6.50% |  |
Senior Notes, face amount |  |  | 394,985
5% Senior Notes Due 2024 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 5.00% |  |
Senior Notes, face amount |  |  | 500,000
5.625% Senior Notes Due 2025 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 5.625% |  |
Senior Notes, face amount |  |  | 500,000
6.75% Senior Notes Due 2026 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 6.75% |  |
Senior Notes, face amount |  |  | 500,000
Senior Notes [Member] | 6.50% Senior Notes Due 2021 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 6.50% |  |
Senior Notes, face amount | $ 344,611 |  | 344,611
Long-term Debt, Fair Value | $ 347,626 |  | 351,682
Senior Notes [Member] | 6.125% Senior Notes Due 2022 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 6.125% |  |
Senior Notes, face amount | $ 561,796 |  | 561,796
Long-term Debt, Fair Value | $ 563,200 |  | 571,627
Senior Notes [Member] | 6.50% Senior Notes Due 2023 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 6.50% |  |
Senior Notes, face amount | $ 394,985 |  | 394,985
Long-term Debt, Fair Value | $ 394,124 |  | 403,434
Senior Notes [Member] | 5% Senior Notes Due 2024 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 5.00% |  |
Senior Notes, face amount | $ 500,000 |  | 500,000
Long-term Debt, Fair Value | $ 466,750 |  | 483,440
Senior Notes [Member] | 5.625% Senior Notes Due 2025 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 5.625% |  |
Senior Notes, face amount | $ 500,000 |  | 500,000
Long-term Debt, Fair Value | $ 473,750 |  | 494,355
Senior Notes [Member] | 6.75% Senior Notes Due 2026 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 6.75% |  |
Senior Notes, face amount | $ 500,000 |  | 500,000
Long-term Debt, Fair Value | $ 497,500 |  | 516,350
Convertible Debt [Member] | 1.50% Senior Convertible Notes Due 2021 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Senior Notes, interest rate, stated percentage | 1.50% |  |
Senior Notes, face amount | $ 172,500 |  | 172,500
Long-term Debt, Fair Value | $ 164,091 |  | $ 168,291

X
- Definition The impairment expense recorded to reduce the value of proved oil and gas assets. + References No definition available. + Details
Name: | sm_ImpairmentofProvedOilandGasProperties
Namespace Prefix: | sm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
Name: | us-gaap_LongTermDebtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A650SeniorNotesDue2021Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A6.125SeniorNotesDue2022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A650SeniorNotesDue2023Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A5SeniorNotesDue2024Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A5.625SeniorNotesDue2025Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A6.75SeniorNotesDue2026Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_ConvertibleDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=sm_A1.50SeniorConvertibleNotesDue2021Domain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |